A secondary or rechargeable battery consists of one or more electrochemical cells, wherein each cell typically includes a positive electrode, a negative electrode, and an electrolyte or other material for facilitating movement of ionic charge carriers between the negative electrode and positive electrode. As the cell is charged, cations migrate from the positive electrode to the electrolyte and, concurrently, from the electrolyte to the negative electrode. During discharge, cations migrate from the negative electrode to the electrolyte and, concurrently, from the electrolyte to the positive electrode.
Such batteries generally include an electrochemically active material having a crystal lattice structure or framework from which ions can be extracted and subsequently reinserted, and/or permit ions to be inserted or intercalated and subsequently extracted.
Typically, multiple electrochemical cells are connected in series or parallel fashion and positioned within a housing to form a battery pack. Larger battery packs (e.g. pack capacity>100 A·hr) may contain hundreds of electrochemical cells, the failure of any one of which may render the entire pack non-functional and irreparable. Accordingly, there is a need for a method and apparatus capable of identifying and isolating a failing or failed electrochemical cell (or string of cells) from the remaining cells, in order to maintain the operability of the remaining cells and, therefore, the pack.